Screw-plug fuse



5. SHAW SCREW PLUG FUSE April 22 1924.

Filed June 28. 192.3

WWW

Patented Apr. 22, 1924.

v UNITED STATES {PATENT OFFICE.

' 'srrnrman SHAW, or raamme'ron, CONNECTICUT, ASSIGNOR 'ro'rnr: JOHNS-PRATT commnx, or nan'rroan; conmcrrcu r, A coarom'rron or connaorrcu'r.

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pplicationflled June as, 1923. Serial nopeaaaoo.

To all whom it may concern:

Be it known that I, STILLMAN SHAW, a citizen of the United States, residing at Farmington, in the county of Hartford and State of Connecticut, have invented a new and useful Improvement in' Screw-Plug Fuses, of which the following isa specification.

This .invention relates to renewable screw plug fuses, that is, those which are so constructed that a new fusible link. can be substituted for one that has been blown.

The object of the inventionisto provide a construction for fuses of this class which is simple and cheap to manufacture and assemble, which is easy to. disassemble andrea-ssemble for substituting a fresh fuse for one that has been destroyed,and which will meet all of the conditions as to safety and-reliability' required of the standard screw plug fuse.

In the accompanying drawings Fig. 1

7 shows a side elevation of a plug fuse conisa view structed according to the invention. Fig. 2

looking atthe bottom of the same. Fig. 3 is a longitudinal section on one plane. Fig.4 is a longitudinal section on a plane at ninety degrees to that of Fig. '3. Fig. 5 isa'perspective view of the removable link carrier.

Thechambered body 1 of the plug is desirably made of porcelain, although it may be made ofother insulating material if desired. The exterior of the cylindrical body is provided with a thread and fitted to screw on and off this thread is the ordinary threaded metallic ring 2 which forms one of the electrical terminals of the plug. Usually these plugs have a transparent disk 3 covering the open end of the chamber in the plug so that the condition of the link in the interior may be clearly observed.

In the embodiment of the invention illustrated the bottom or closed end of the plug is mortised so as to provide a diametrical slot 4 through the closed end of the plug into the chamber. The fuse carrier 5 is a thin block or flat piece of thick sheet insulatto project through the slot into the chamber in the body, and a downwardly extending boss 8 desi' ned toproject between and a little below the osses 9 on the end of the body at the sides of the mortise. I

The fusible element 10 is shown as a flat link out from sheet metal, as-zinc, but it may be a round wire, if desired. One end of the link is folded around the under edge at the middle of the boss 8 of the carrier and the other endv of the link is folded around the side edge of one of the wings 6, the intermediate section of the link being looped up over one of the teats 7. When the carrier provided withthelink attached in this manner is inserted into the mortisein the end of the body the loop of the link extends upward to the vicinity of the window that closes the chamber. The end'of the link that is folded around the boss forms the central electrical contact of the plug while the end of the link that is folded around thewing is in position to be engaged by and make electrical contact with the threaded metallicring. When the ring is screwed onto the body of the plug the fiangle 11 atits lower end fits over the wings of t e carrier so as to hold it in place, the flange of the ring at the same time engaging the end of the link'at the side of the carrier. Notches 12 may be made in the edges of the boss 8 so that the carrier may beconveniently grasped and removed from the mortise when the threaded ring is unscrewed from the body of the plug. 7

The mortise in the end of the body of this plug is readily formed and the carrier is of simple shape and cheaply made. It is an easy operation to bend the. ends of the fusible link about thecarrier so that one end provides the central electrical terminal and the other end completes the circuit through the metallic threaded ring, while the loop is of suflicient length and so spread that the link will properly function and there will be no danger of establishing a destructive are when the fuse blows.

The invention claimed is 1. A plug fuse comprising a chambered body of insulation'having a threaded exterior and a slot through its bottom end, a link carrier of insulation loosely extending through said slot, a fusible link with one end bent over the bottom edge at the center of the carrier and its other end bent around one of the side edges of the carrier, and a threaded metallic ring removably screwed upon the body and electrically engaging with the link and retaining the carrier in position. i

2. A plug fuse comprising a chambered body of insulation having a threaded exterior and a mortise extending across the bottom end of the chamber, a link carrier of insulation loosely fitting said mortise, a fusible link'with one end bent over the bottom edge at the center of the carrier and its other end bent over one of the side edges of the carrier, and a threaded metallic ring reinovably screwed upon the body and electrically engaging with the end of the link at the side edge of the carrier and holding the carrier in position.

3. A plug fuse comprising a chambered body of insulation having a threaded exterior and a mortise extending across the bottom end of the. chamber, a link carrier of insulation having a downwardly extending boss and outwardly extending wings loosely fitting said mortise, a fusible link with one end bent around said boss and its other end bent around one of said wings, and a threaded metallic ring removably screwed upon the body and engaging said wings for holding the carrier in place, said ring being in electrical engagement with the fusible link.

4. A plug fuse comprising a chambered body of insulation having a threaded exterior and a mortise extending across the bottom end of the chamber, a link carrier of insulation having a downwardly extending boss, outwardly extending wings and upwardly extending teats fitting said mortise, a fusible link looped over one of said teats and having one end bent around one of said wings and its other end bent around the said boss, and a threaded metallic ring removably screwed upon the body and engaging said wings for holding the carrier in place, said link being in electrical engagement with the fusible link.

5. A plug fuse comprising a chambered body of insulation having a threaded exterior and a mortise extending across the bottom end of the chamber, a flat block of insulation fitting said mortise, a flat fusible link with one end bent around the bottom edge and its other end bent around one side edge of said block, and a threaded metallic ring removably screwed upon and holding said block in position, said ring being in electrical engagement with an end of the fusible link.

6. A plug fuse comprising a chambered body of insulation having an exterior thread and a slot through its bottom end, a transparent disk covering the top of the chamber, a link carrier of insulation loosely occupying said slot, a fusible link with one end bent around the bottom at the center of said carrier and its other end bent over one of the side edges of the carrier, and a threaded metallic ring removably screwed upon the body and electrically engaging with an end of said link.

7. A plug fuse comprising a chambered body of insulation having a threaded exterior and a mortise extending across the bottom end of the chamber, a link carrier of insulation having a downwardly extending boss, outwardly extending wings and upwardly extending teats loosely fitting said mortise, and a threaded metallic rin removably screwed upon the body an engaging said wings for holding the carrier in place.

8. A plug fuse comprising a chambered body of insulation having a threaded exterior and a slot through its bottom end, a link carrier of insulation loosely fitting said slot, a fusible link with its ends bent about said carrier, one end providing the center contact of the plug, and a threaded metallic ring'removably screwed upon the body and engaging the other end of the link and holding the carrier in osition.

STILL AN SHAW. 

